A lathe makes the rough cutting of a blank faster and puts a better surface finish on the work if you have a through-the-bore lubrication setup, like Greg Tannel's stuff. However, it is also easy to screw up on a lathe, overcutting, for one. I've seen some clueless guys put a reamer directly in a tailstock drill chuck, then wonder why they keep getting chambers that are too fat in the rear? It takes more knowlege and tooling to do well on a lathe, though it takes more sense of "feel" to do it freehand.
If you have a rough-chambered barrel, I have had very good luck with the pull-through style finishing reamers in service rifles, and can recommend that route. All hand reaming of roughed-in chambers presumes your rough cut was made properly concentric with the bore axis. If you know someone with a lathe, you might at least consider having them indicate a rough chamber for concentricity so you may return the barrel if it is crummy? Crummy would be in the same range as that of loaded cartridge bullet runout which affects accuracy - 4 mils or more total indicated runout (TIR). Great would be half mill and under TIR. One to two mils is not uncommon.
Nick
